The "four C's" refer to Colour, Clarity, Cut and Carat. It is the combination of these four factors that determines a diamond's performance and beauty.

5th, 6th and 7th C’s
There is more to guide the buyer in his/her selection of a diamond.

Colour is graded on the scale developed by the GIA and is almost universally used today to classify diamonds in the world market. The normal range of this alphabetic scale starts at D (Colourless) and runs through Z (light yellow or brown). Colourless stones are rarer and more valuable than stones with body Colour in the normal range. However, diamonds graded as fancy are analyzed differently and can be extremely valuable.

It is helpful to think of the scale in terms of grade ranges: D,E,F are considered Colourless, G,H,I,J are near-Colourless and lower grades are slightly tinted to lightly tinted.

In addition to the increased rarity and value of Colourless stones, body Colour also impacts the quality of light emanating from a diamond. Body Colour acts as a sort of filter that diminishes to an extent the pure nature of light returning to the eye. Colourless diamonds that are well-cut exhibit the best spectral display or fire.

Although lower Colours can still be very beautiful Gem Diamond Company prefers to sell only diamonds of J Colour and above.

Florescence:
Flourescence, also known as photoluminescence, is a property in some diamonds that causes them to glow when exposed to ultraviolet light. The effect is rarely noticeable under normal circumstances and is chiefly an identifying characteristic of a given diamond. In many cases flourescence is a benefit, helping lower Colours to appear whiter, but in rare cases it is detrimental, causing the stone to look slightly foggy in certain light.

Practical advice:
While Colourless stones are rarer and cost more, near-Colourless stones will look essentially the same to the eye when set in jewelry. Choosing a GHIJ Colour instead of one in the DEF range will enable you to get a larger diamond for the money, without a substantial compromise in performance or beauty. If the diamond is to be set in white gold or platinum, aim a little higher on the scale than you would if setting it in yellow gold. Yellow gold disguises body Colour whereas white metal reveals it.

Blue flourescense can add to eye appeal of near-Colourless diamonds and therefore be a benefit. Very strong fluorescence will not enhance Colourless stones and may detract from their beauty and value.

Diamonds are graded for clarity based upon the number, size and location of these tiny inclusions. They also serve to create a very unique identifying signature for a specific diamond, much like a fingerprint.

The clarity grading system most widely used around the world is the GIA scale. Professional grading is done in controlled conditions under 10X magnification.

Carat weight is stated decimal terms, such that one carat is written 1.00ct. One and a half carat = 1.50ct, three quarters of a carat = .75ct and so on.

Diamonds under one carat are commonly talked about in terms of points which are simply percentage points of a carat (1.00ct= 100 points). So a quarter of a carat (.25ct) is said to be 25 points, half carat is 50 points, .98ct is 98 points and so on. Because a carat is a unit of weight, diamonds of exactly the same carat weight can appear to be different sizes, depending on the proportions of the cut. A thicker or deeper cut will look smaller than a stone with a larger surface area or "spread".

The illustration below shows relative visual sizes of well cut diamonds in a range of carat weights. (not intended to represent actual sizes)

Note: Carat is sometimes confused with Karat (and for good reason!). Whereas carat is a measure of gemstone weight, Karat is a measure of gold purity. 24 Karat is pure gold, 14K is 14/24 pure (58.5%), 18K is 18/24 pure (75%).

Practical advice:
Apparent diamond size varies depending on the carat weight and the proportioning of the cut. A 1.00ct stone that is cut a little too deep might actually be smaller looking than a .90ct stone that is well proportioned. Also, at certain carat levels, per carat prices increase substantially. It is sometimes possible to get real price savings by staying just under these so called magic marks. For instance, a well cut stone of .45 ct might be quite a bit less expensive than the same quality .50ct, yet have a visual appearance virtually the same. The important magic marks are .50ct ,.70ct, 1.00ct, 1.25ct, 1.50ct, 2.00ct, 3.00ct, 5.00ct.

In addition, a cutter will usually have to sacrifice more of the rough stone to produce a well cut finished stone, thereby ending up with a smaller diamond than had he taken liberties with the cut. Well cut stones therefore yield less weight from the rough and are therefore more expensive to produce.

Fire, Brilliance and Scintillation
These are the three aspects of diamond performance and they are distinct elements.

Fire refers to a diamond’s ability to act as a prism and to break white light into its spectral colors. Diamonds with good fire will exhibit little sparks of red, green, yellow and blue as light refracts through and out of the stone to the eye.

Brilliance is the total amount of light returned to the eye and results in the overall brightness of the stone.

Scintillation is the sparkle of the diamond and is determined by the cutting style and execution of the cut.

The quality of a diamond’s cut is a complicated interaction of proportions and finishing factors. Many combinations can result in beautiful finished stones. Because the above mentioned performance elements are distinct, it is possible for the cutter to make tradeoffs in the process. For instance, making the table facet a little larger may make the stone slightly more brilliant and slightly less fiery. So while there are cut guidelines, in the end beauty is in the eye of the beholder.

Note: The word cut is also used in reference to a diamonds shape- round cut, marquise cut, princess cut, etc. It is less confusing to restrict the term cut to a discussion of the proportions, alignment and finish of a polished diamond.

The following illustrations show the various parts of a diamond and the measurements used in the analysis of a diamonds cut:

Additionally, two other factors in the detailing of the diamond are important in fine tuning the final product. Symmetry refers to the alignment of the facets with one another, and polish refers to the final mirror finish achieved all the facets.

Ideal, super ideal, triple o, hearts and arrows, branded and signature cuts
As if the subject of cutting was not complicated enough, now there are an ever increasing number of competing ideas about what cutting parameters are truly the best.

The concept of an ideal cut first gained popularity in 1919 when mathematician Gabriel Tolkowsky published a study of the behavior of light in a cut diamond and came up with a formula for proportions that would result in the most beautiful round diamond.

Over the years experimentation and scientific study have revealed that there are many proportion combinations that result in superb finished diamonds. In fact, the most important study on the subject ever conducted and utilizing advanced computer modeling technologies is the ongoing study by the Gemological Institute of America.

Despite all the hype in the trade as different companies go about promoting their own versions of ideal diamonds, the position of the GIA on the subject is stated in their educational materials in this way: Unfortunately, there is no proof that any one set of proportions is truly ideal. Preliminary results of ongoing research on cut suggest that many different proportion combinations succeed equally well.

For this reason, GIA does render qualitative cut grades on their reports.

To underscore how complicated the subject is, despite advanced research no definitive conclusion has been reached regarding the round brilliant cut. Fancy shapes offer a mind numbing range of different variables that may defy definitive pronouncements for generations to come!

Fancy Shapes
Diamond shapes other than round are referred to as fancy shapes. Almost any shape is possible and there are new designs coming into the market regularly as new diamond cutting technologies are developed. Determining a cut grade for fancy shapes is far more complicated than for rounds, and as a result there are no rigid standards, and therefore no “ideal” or “premium” combination of proportions. To a great extent with fancies, ‘beauty is in the eye of the beholder’.

One of the most important aspects in fancies is the overall outline of the shape. The diamond's outline will affect the eye appeal of the stone as well as the overall design of a finished piece of jewelry. Yet this remains a relatively subjective factor.

For instance, some people might prefer a long slender marquise for a design that accentuates a long slender finger. Likewise, A pendant design might favor an elongated pear shape over one with broad shoulders.

To help you understand and visualize the outline of the stone, we have included a calculation of the length to width ratio for all our fancies on each diamond detail page. In addition, we present a representative image of a diamond with a length to width ratio similar to the diamond being viewed. By knowing the length to width ratio of the diamond in the representative image and comparing that to the ratio of the actual diamond, you are able to get a very close visualization of the outline of the actual diamond under consideration.

For example, if you are looking at a marquise shape stone and the representative image has a ratio of 1.78, and you see in the diamond details that the actual stone has a ratio of 1.85, you know that the diamond you are considering is very slightly more elongated than the representative image. Likewise, if you are looking at an oval and the representative image is 1.45, and the actual diamond has a ratio of 1.39, you know that the stone you are considering is slightly wider than the diamond in the representative image.

We hope that you find this tool helpful in selecting the fancy shape best for your taste and best suited to the piece of jewelry that you wish to create.

There is more to guide the buyer in his/her selection of a diamond.

CERTIFICATION
The grading of a diamond is not an exact science: One cannot put a diamond into a machine and get a clarity grading for example. Therefore, to give their clients peace of mind with regard to the grade of stone they are buying, most reputable dealers will have their stones submitted to an independent, internationally recognised professional diamond grading laboratory where the stones are graded by trained gemologists under strict and standardised conditions. The diamond is then issued with a uniquely numbered certificate stating size, colour & clarity. It will also contain a proportions analysis (all the data relating to how well the stone is made), and on larger stones (>0.37ct) the certificate will also have a plot (like a fingerprint) of all the inclusions and their positions.

In South Africa, we use three laboratories:

• The Jewellery Council Laboratory
• The European Gemological Laboratory
• The Diamond Institute of Africa
  

CONFIDENCE
In many ways, this is the most important “C” in helping a buyer choose a stone.

Even armed with a good knowledge of the 4 C’s. a buyer may still be unsure what they are looking for. As a rough example, the same amount of money will buy any of the following stones: a third of a carat D-Flawless, a half carat H VS2, a three quarter carat K SI2, or a 1 carat L P2. This shows that there is a huge tradeoff between size, colour & clarity, and the stone that is right for one buyer will not be right for another: The buyer needs confidence in his dealer to assist him/her in making the right choice. A good jeweller will be able to show the stone off to best advantage: Judicious use of metals in the setting can enhance the colour, and the correct setting can disguise or hide inclusions. The laws of physics tell us that you cannot have maximum life and maximum fire in the same stone: There must always be some tradeoff. Some stones are slightly larger in diameter than the ideal proportions would suggest, making them look bigger. Some stones have smaller than ideal crowns, but they tend to be very lively. Your dealer should be able to help you judge these things objectively. Many stones are not certified by independent laboratories, and in these cases, one needs to have confidence that the stone really is what the dealer says it is. Reputable dealers tend to be strict with their own gradings of stones and allow clients recourse if later laboratory gradings are significantly different from their own. Although naturally occurring coloured diamonds are very rare, artificially coloured stones (done using heat and/or pressure and/or radiation) are increasingly common. These colours can be very intense and beautiful, but they are less valuable. It is accepted practice among reputable dealers in this country to clearly state that the stone is artificially enhanced, as it is to reveal the presence of laser drilling and/or fracture filling to improve clarity.

A 7th C for South Africa….COST

As producers of a high percentage of the world’s finest quality gemstones, coupled with an economy that favours the international visitor, South Africa can supply diamonds to the market at excellent rates. Compare prices here to those in the international diamond centres of the world such as Hatton Garden in London, and see value of purchasing stones in South Africa.